The invention relates to novel soluble pigment precursors possessing not only higher thermal stability but also improved solubility characteristics and to a process for mass coloration of high temperature polymers that utilizes these novel soluble pigment precursors.
Soluble pigment precursors and their thermal decomposition in situ, for example in a photosensitive composition, a polymer, an aqueous dispersion, a porous material or a surface, to form pigments having superior properties are known from EP-A-0 648 770, EP-A-0 648 817, EP-A-0 654 506, EP-A-0 654 711, EP-A-0 742 255, EP-A-742 556, EP-A-0 761 772, EP-A-0 764 628, EP-A-0 892 018, EP-A-0 718 697, WO-98/32802, WO-98/45756, WO-98/45757, WO-98/58027, WO-99/01511 and WO-99/01512.
However, it has been determined that these soluble pigment precursors do not adequately meet the highest requirements. For instance, many pigment precursors, some of them readily soluble, are thermally impossible to convert selectively and quantitatively into the desired pigments. Other pigment precursors conversely combine excellent thermal convertibility with undesirably low solubility.
It has been found that, surprisingly, there is a previously unrecognized possibility of combining good solubility and superior thermal properties of pigment precursors by using novel substitution pattern. The novel compounds are highly mobile below their starting decomposition temperature and provide technically significant, in certain cases even unique application advantages as detailed hereinbelow.
The invention accordingly provides a compound of the formula
A(B)xxe2x80x83xe2x80x83(I)
where x is an integer from 1 to 8,
A is the radical of a chromophore of the quinacridone, anthraquinone, perylene, indigo, quinophthalone, indanthrone, isoindolinone, isoindoline, dioxazine, azo, phthalocyanine or diketopyrrolopyrrole series, this radical being linked with x B groups via one or more heteroatoms, these heteroatoms being selected from the group consisting of N, O and S and forming part of the radical A, and
B is hydrogen or a group of the formula 
although at least one B group is not hydrogen and when x is from 2 to 8 the B groups may be identical or different,
E1 is oxygen or is selected from the group consisting of methylene, methyleneoxy and ethylene, each member of the group being unsubstituted or substituted by one R5 or by 2 radicals, R5 and R6, or is two separate radicals, R7 and R8, R7 being attached to the same atom as R1 and R8 to the same atom as R4,
E2 is selected from the group consisting of methylene, ethylene, propylene and butylene, each member of the group being unsubstituted or substituted by one R9 or by 2 radicals, R9 and R10, or is two separate radicals, R11 and R12, R11 being attached to the same atom as R1 and R12 to the same atom as R4,
G1 is O or N(R13),
R1 is hydrogen, methyl, ethyl, methoxy or ethoxy,
R2 and R3 are independently hydrogen, C1-C8alkyl, C1-C8alkoxy, C1-C8alkoxy-C2-C8alkylene or C1-C8alkoxy-C2-C8alkyleneoxy,
R4 is hydrogen, C1-C8alkyl, C1-C8alkoxy, C1-C8alkoxy-C2-C8alkylene, C1-C8alkoxy-C2-C8alkyleneoxy, C5-C6cycloalkyl, C5-C6cycloalkoxy, phenyl, phenoxy or a 5- or 6-membered, saturated or singly to triply unsaturated heterocyclic radical,
R5, R6, R9, R10 and R12 are independently C1-C8alkyl or C1-C8alkoxy, or R6 and R9 together are a direct bond,
R7 and R8 are independently hydrogen, C1-C8alkyl, C1-C8alkoxy, C1-C8alkoxy-C2-C8alkylene or C1-C8alkoxy-C2-C8alkyleneoxy,
R11 is hydrogen, C1-C8alkyl or C1-C8alkoxy,
R13 is methyl or ethyl, and
R14 is C1-C8alkyl, C5-C6cycloalkyl, phenyl or a 5- or 6-membered, saturated or singly to triply unsaturated heterocyclic radical,
it being possible for two methoxies attached to the same carbon atom to combine and form 1,2-ethylenedioxy, or for methoxy to combine with ethoxy attached to the same carbon atom to form 1,2- or 1,3-propylenedioxy, or for methoxy or ethoxy to combine with ethoxy attached to xcex1- or xcex2-enchained carbon to form dimethylmethylene,
and where additionally
a) R1, R2, R3, R7 or R11 is hydrogen, and
b) when E1 is two separate radicals R7 and R8 and E2 is methylene or ethylene at least one of the following further conditions applies:
R1, R2, R3, R4, R7, R8, R9 or R10 is methoxy or ethoxy;
R2, R3, R4, R7, R8, R9 or R10 is secondary C3-C8alkyl or tertiary C4-C8alkyl or C3-C8alkoxy;
R2, R3, R7 or R8 is C1-C8alkoxy-C2-C8alkylene or C1-C8alkoxy-C2-C8alkyleneoxy; or
R4 is C5-C6cycloalkyl, C5-C6cycloalkoxy, phenyl, phenoxy or a 5- or 6-membered heterocyclic radical.
As is evident from this definition, substitution is of major significance for cyclic compounds.
C1-C8Alkyl, including in C1-C8alkoxy, is for example methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl, tert-butyl or any isomer of pentyl, hexyl, heptyl or octyl, such as tert-amyl or tert-octyl. C1-C8Alkyl is preferably secondary C3-C8alkyl or tertiary C4-C8alkyl. C5-C6Cycloalkyl, including in C5-C6cycloalkoxy, is cyclopentyl or cyclohexyl.
C2-C8Alkylene, including in C1-C8alkoxy, may be straight-chain, branched or cyclic. Examples are 1,2-ethylene, 1,2-propylene, 1,3-propylene, an isomer of butylene, pentylene, hexylene, heptylene, octylene or cyclopentylene, cyclohexylene or cyclooctylene.
5- or 6-membered, saturated or singly to triply unsaturated heterocyclic radicals are for example 2- or 3-furyl, 2- or 3-thienyl, 1-pyrryl, 2H-2-pyrryl, 2H-2-pyranyl, 4H4-pyranyl, 2- or 4-pyridyl, 1-, 2-, 3- or 4-piperidyl, 1-, 2- or 3-pyrrolidinyl, or any isomer of imidazolidinyl, imidazolinyl, pyrazolidinyl, pyrazolinyl, pyrazolyl, quinuclidinyl, pyrazinyl, pyrimidinyl, pyridazinyl, morpholinyl, furyl, dihydrofuryl, tetrahydrofuryl, dihydropyranyl or tetrahydropyranyl.
Examples of bicyclic groups on the carboxyl group in the formula (II) are cyclic terpene radicals, such as thujyl, caryl, pinyl, bornyl, norcaryl, norpinyl or norbornyl.
E1 is preferably oxygen, methylene or two separate radicals R7 and R8, especially methylene or two separate radicals R7 and R8.
E2 is preferably ethylene or two separate radicals R11 and R12.
G1 is preferably O.
R1 is preferably hydrogen, methyl, ethyl, methoxy or ethoxy.
R2, R3 and R4 are preferably hydrogen or C1-C8alkyl.
R5, R6, R9, R10 and R12 are preferably methyl, secondary C3-C8alkyl or tertiary C4-C8alkyl.
R7, R8 and R11 are preferably hydrogen or methyl, especially hydrogen.
R14 is preferably C1-C8alkyl.
Preference is given to B groups which exclusively of the carboxyl group contain at most 3 further oxygen atoms, especially no or 1 to 2 further oxygen atoms, particularly preferably no or 1 further oxygen atom. When a B group exclusively of the carboxyl group contains 2 or 3 further oxygen atoms, it is preferable for no carbon atom in this B group other than in the carboxyl group to be bonded to more than one oxygen atom.
Preference is given to groups of the formulae (II) or (III) which are asymmetrical. Particular preference is given to groups of the formulae 
where R15 is xe2x80x94CR1R7R11 and R16 is xe2x80x94CR2R3xe2x80x94CR4R8R12 or xe2x80x94CR2R3xe2x80x94G1R14, and R2, R3, R4, R7, R8, R9 or R10 is secondary C3-C8alkyl or tertiary C4-C8alkyl, especially tert-butyl, tert-amyl or 2,4-dimethyl-2-pentyl.
Very particular preference is given to groups of the formulae (II) and especially (IV).
The compounds of the invention are notable for improved thermal characteristics. At temperatures of about 140xc2x0 C. to about 220xc2x0 C., customary during incorporation into many polymers, they will disperse therein very homogeneously, usually with complete dissolution, without decomposing into the pigment. On cooling they crystallize back out within the polymer. This provides, for example with the diketopyrrolopyrroles, excellent, particularly homogeneous colour and/or fluorescent pigmentations.
On the other hand, the compounds of the invention decompose very smoothly at temperatures of about 220 to 300xc2x0 C. As a result, prolonged heating, which may harm the polymers, can be substantially or completely avoided. In addition, finer, even more transparent, isometric and less dichroic pigment particles are obtained than with prior art pigment precursors, which is of particular advantage in fibres and in injection moulding processes in particular.
The invention accordingly further provides a process for mass coloration of a polymer, which comprises adding at least one compound of the formula (I) to the polymer before or during processing, the processing taking the form of extrusion, injection moulding or fibre spinning at 220 to 330xc2x0 C., preferably at 250 to 320xc2x0 C., especially 280 to 300xc2x0 C.
As mentioned above, the compounds of the invention form pigments very rapidly at high temperatures. However, it has highly surprisingly been discovered that their colour already starts to change at much lower temperatures. Depending on the temperature, it is possible to get different colours as illustrated by some of the examples which follow. The intermediate colours are likely due to partially decomposed compounds of the formula (I); it could be due either to the simultaneous presence of compounds of the formula (I) and pigments of the formula A(H)x (VI) or to the presence of some intermediates. Preferred chromophores for intermediate colours are quinacridones, perylenes, indigos, azos and phthalocyanines, most preferred the quinacridone and indigo chromophores.
The intermediate colours are attractive and can be used purely for decorative purposes. By heating to higher temperatures, they can be further transformed into the pigmentary colour, thus enabling them to be used in thermochromic media, in particular in security items. A preferred use is the selective coloration in the mass of one or more polymeric parts of a composite item, for example to a transparent film, tape or patch of arbitrary shape laminated between the support and the transparent cover of a security item such as but not restricted to identity, bank, credit or company cards, checks, banknotes, driving licenses or any other badges, pass or permits. Counterfeiting security items comprising the instant intermediate, thermochromic colours becomes much more difficult for reasons evident to a person skilled in the art but which should of course not be disclosed to potential counterfeiters.
The invention accordingly also provides a thermochromic material comprising a polymer coloured in the mass by a product obtainable by partial thermal decomposition of a compound of the formula (I) or by two compounds, selected from the group consisting of compounds of the formula (I) and pigments of the formula A(H)x (VI). In a preferred embodiment, said material is comprised within a composite, especially a security item.
The polymer is preferably a polyolefin, polyester or polyamide, especially polypropylene, or some other engineering plastic, for example a polyimide, polysulfone, polyether sulfone, polyphenylene oxide, polyarylene, polyarylene sulfide, polyepoxide, polyphenylene oxide or ABS.
In addition, many compounds of the formula (I) have a melting point which is lower than the decomposition point, although the latter is none the less still located in a useful range below the onset of decomposition of the material to be pigmented. This allows pigmentation of all sorts of materials, for example porous metal oxide layers or sintered materials as described in WO-00/27930 or EP-00810309.5, in significantly higher colour strength. Pigment coatings, as disclosed in EP-A-0 742 556, can also be produced on a smooth surface, in which case the improved thermal properties of the compounds of the formula (I) ensure that astonishingly good results are obtained.
The invention accordingly also provides a process for pigmenting a porous material, which comprises at least one compound of the formula (I), in liquid form or dissolved in an inert liquid in a weight concentration of at least 25%, penetrating into the pores of the porous material and thereafter being thermally converted into a pigment of the formula A(H)x (VI).
Useful solvents include for example hydrocarbons, alcohols, amides, nitriles, nitro compounds, N-heterocycles, ethers, ketones and esters and may be singly or multiply unsaturated or halogenated. Examples are methanol, ethanol, isopropanol, diethyl ether, acetone, methyl ethyl ketone, 1,2-dimethoxyethane, 1,2-diethoxyethane, 2-methoxyethanol, ethyl acetate, tetrahydrofuran, dioxanes, acetonitrile, benzonitrile, nitrobenzene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, pyridine, picoline, quinoline, trichloroethane, benzene, toluene, xylene, anisole and chlorobenzene. Further examples may be taken from standard works. The solvent may also be a mixture of 2 or more, for example 3 to 5, liquids. Further details may be taken from WO-98/58027 or WO-00/36210.
The compounds of the formula (I) may also be employed with significant practical benefits, readily apparent to those skilled in the art from the improved thermal characteristics, in reactive extrusion, colour filters, thermodiffusion media, ink-jet printing dispersions, electrophotographic photoreceptors or for colouring wood, these processes being known per se for example from EP-A-0 654 711, EP-A-0 718 697, EP-A-0 892 018, WO-98/45756, WO-98/58027, WO-99/01511 or WO-00/36210, although the imperfect combination of the physical properties (especially solubility decomposition point) of previously known compounds did not lead to fully satisfactory results.
The compounds of the formula (I) may be used individually or else in the form of mixtures with other compounds of the formula (I) or with other pigment precursors, for example those disclosed in EP-A-0 648 770, EP-A-0 648 817, EP-A-0 654 506, EP-A-0 742 255, EP-A-0 761 772, WO-98/32802, WO-98/45757, WO-99/01512, WO00/17275 or PCT/EP-00/03085.
This can be used to produce, for example, solid solutions or mixed crystals, in which case host and guest components having identical or else different decomposition points can be used, depending on the desired objective. When host and guest components having different decomposition points are used, the decomposition point of the host component may be lower or higher than those of the guest components.
A preferred embodiment is the use of binary or ternary mixtures including 60 to 99.9% by weight of a compound of the formula (I) and 0.1 to 40% by weight of one or two thermally more labile compounds of the same chromophore class with an Axe2x80x2 that differs from A, preferably a binary mixture of 99.5 to 95% by weight of a compound of the formula (I) and 0.5 to 5% by weight of a thermally more labile compound of the same chromophore class with an Axe2x80x2 that differs from A.
The thermally more labile compound of the same chromophore class with an Axe2x80x2 that differs from A is particularly preferably a compound of the formula 
where xxe2x80x2 is an integer from 1 to 8 and Axe2x80x2 is the radical of a chromophore of the quinacridone, anthraquinone, perylene, indigo, quinophthalone, indanthrone, isoindolinone, isoindoline, dioxazine, azo, phthalocyanine or diketopyrrolopyrrole series, this radical being linked with xxe2x80x2 xe2x80x94COOR17 groups via one or more heteroatoms, these heteroatoms being selected from the group consisting of N, O and S and forming part of the radical Axe2x80x2 and R17 being any desired tertiary group. As particularly customary R17 radicals there may be mentioned by way of example tert-butyl, tert-amyl, 2-methyl-3-buten-2-yl, 2-methyl-3-butyn-2-yl, 4-oxa-2-pentyl or 4,7-dioxa-1-methyl-2-octyl, this being just a small selection of known radicals which are cited in the above-cited publications, which are hereby expressly incorporated herein for further examples.
Very particular preference is given to compounds of the formula (VII), whose basic structure Axe2x80x2(H)xxe2x80x2(VIII) is known to lead to synergistic effects with the basic structure A(H)x (VI) of the compound of the formula (I), the known effect being much intensified when the compounds of the formula (I) have higher decomposition temperatures than the compounds of the formula (VII). This is very surprising because one would expect on the contrary that the effect would be at its most intense when the compounds of the formula (I) and (VII) thermally decompose to the pigment at one and the same time (see JP-A-11/305032).
An example of this is the use of mixtures of two 1,4-diketo-3,6-diarylpyrrolo[3,4-c]pyrroles of the formulae (I) and (VII) where aryl is phenyl, chlorophenyl, dichlorophenyl, tolyl, p-cyanophenyl, tert-butylphenyl or biphenyl in the formula (I) and m-cyanophenyl in the formula (VII). Corresponding compositions comprising A(H)x (VI) and Axe2x80x2(H)xxe2x80x2 (VIII) are known from EP-A-0 748 851.
It is particularly in polymers that are processed at a temperature of at least 220xc2x0 C., for example polypropylene at 240 to about 330xc2x0 C., that these mixtures provide very surprising advantages in transparency and colour properties, specifically colour strength and saturation, especially and particularly by comparison with the corresponding known compositions.
The compounds of the formulae (I) may be prepared in a conventional manner from known pigments and chloroformic esters or pyrocarbonates obtainable analogously to known processes. Known processes for preparing pyrocarbonates useful as starting materials for pigment precursors are disclosed for example in EP-A-0 764 628 or CH-2585/98.
A is the radical of known chromophores having the basic structure A(H)x (VI), although on every heteroatom linked to x B groups A preferably has at least one immediately adjacent or conjugated carbonyl group, for example 
and also in each case all known derivatives thereof, as for example disclosed in the abovementioned patent applications or described by Willy Herbst and Klaus Hunger in xe2x80x9cIndustrial Organic Pigmentsxe2x80x9d (ISBN 3-527-281614, VCH/Weinheim 1993).
Particular utility is possessed by those soluble chromophores wherein the basic structure A(H)x (VI) is Colour Index Pigment Yellow 13, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 94, Pigment Yellow 95, Pigment Yellow 109, Pigment Yellow 110, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 139, Pigment Yellow 151, Pigment Yellow 154, Pigment Yellow 175, Pigment Yellow 180, Pigment Yellow 181, Pigment Yellow 185, Pigment Yellow 194, Pigment Orange 31, Pigment Orange 71, Pigment Orange 73, Pigment Red 122, Pigment Red 144, Pigment Red 166, Pigment Red 184, Pigment Red 185, Pigment Red 202, Pigment Red 214, Pigment Red 220, Pigment Red 221, Pigment Red 222, Pigment Red 242, Pigment Red 248, Pigment Red 254, Pigment Red 255, Pigment Red 262, Pigment Red 264, Pigment Brown 23, Pigment Brown 41, Pigment Brown 42, Pigment Blue 25, Pigment Blue 26, Pigment Blue 60, Pigment Blue 64, Pigment Violet 19, Pigment Violet 29, Pigment Violet 32, Pigment Violet 37, 3,6-di(4xe2x80x2-cyano-phenyl)-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-di(3,4-dichloro-phenyl)-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione or 3-phenyl-6-(4xe2x80x2-tert-butyl-phenyl)-2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione.
Mention may be made in particular of 3,6-diaryl-pyrrolo[3,4-c]pyrrole-1,4-diones of the formula (I) that contain 2 groups of the formula (II).
The compounds of the formula (I) according to the invention are also very useful fluorescent dyes for mass coloration of high molecular weight organic material which are processed at a temperature of about 140xc2x0 C. to 220xc2x0 C.
Examples of useful high molecular weight organic materials that can be fluorescent-coloured with the compounds of the formula I according to the invention are vinyl polymers, such as polystyrenes, polyacrylates, poly(vinyl chloride), poly(vinyl fluoride), poly(vinyl acetate), poly(alkyl vinyl ether)s, polyurethanes, polyolefins, polyalkadienes and polycarbonates. High molecular weight organic materials can be of natural or artificial origin and customarily have a molecular weight in the range from 103 to 108 g/mol.
Based on the high molecular weight organic material to be coloured, the compounds of the formula (I) according to the invention can be used in an amount of 0.01 to 30% by weight, preferably 0.1 to 10% by weight.
If appropriate, customary additives, such as stabilizers, plasticizers, fillers or other colour-conferring ingredients, such as white, colour or black pigments, may also be added in any desired customary amounts. The coloured material is then brought to the desired final form in a conventional manner, such as calendering, pressing, extruding, coating, casting, injection moulding or powder coating.
The fluorescent colourations obtainable thereby are notable for particularly high quantum yield and homogeneity.
The invention accordingly further provides high molecular weight organic material having a glass transition point (Tg) of 140xc2x0 C. to 220xc2x0 C. and containing in its bulk 0.1 to 10% by weight of a compound of the formula (I), based on the total weight.